Dental porcelain is a relatively strong ceramic material which is insoluable in oral fluids and has excellent aesthetic qualities. It is formed from a fine ceramic powder which has been pigmented to produce the color and translucency of human teeth, and which has been formed into a paste and fused to form the ceramic body. Because porcelain has excellent tissue compatibility and a relatively long lasting life, porcelain and porcelain processing techniques have been used for artificial teeth, inlays, crowns, bridges, and complete dentures.
Porcelain has been limited in its effectiveness in restorative procedures primarily by the major undesirable characteristics of the material, namely brittleness. Due to the brittle nature of porcelain, patients who have permanent attachment of porcelain dental appliances in the mouth often suffer the agony of having fractured porcelain. While the fracture oftentimes does not cause direct pain, a great deal of time, money and dental effort is expended to repair broken porcelain appliances. For example, when a porcelain jacket crown becomes fractured, usually the entire appliance has to be removed and a new appliance made, which is then reattached with a cement.
Some efforts have been made recently to employ polymeric composite materials to restore the defective part of a broken porcelain appliance without removing the appliance from the patient's mouth. This newly attempted technique involves the use of mechanical abrasion to roughen up the surface of the porcelain, followed by application of a silane adhesion promoter with a final step of applying a polymeric composite restorative material with an adhesive. While this method substantially reduces chair time and cost, the composite material many times is not adequately bonded to the porcelain and falls off due to stress and insufficient adhesion. Mechanical roughening improves adhesion, but is ineffective in introducing the microcrevices necessary for positive mechanical locking by the composite materials. Furthermore, there is always the risk of further chipping the porcelain during the roughening-up process, which is usually done by a dental bur.